I would rather say its a bug in the game if its reacting to some tab discarding option in a browser thats set by default to be on ;).
Also description says something about discarding tabs from memory if system memory is low. With 16gb of ram even lazy Nutaku developer wouldn't fuck up browser games so much to eat all of that. But I will check if thats what causes the pausing.
Like I thought its not that. Game still pauses when I go and focus a different tab. Well at least I switched some 2D canvas GPU rendering for test and it seems to help with a bit lagy animations (especially in FKG/Senguko if a lot of tabs is open tend to kinda slow down).
100 jewels for 10 more slots for either weapons or girls in shop (right menu).